1. Field of Invention
The present invention is generally directed to imaging members, such as photoconductive imaging members and which members are comprised of novel charge transport layer binders of, for example, poly(imide-carbonate)s. The aforementioned poly(imide-carbonate) binders can possess a number of advantages including, for example, resistance to mechanical and corrosive wears induced and caused by the application of the electrochemically aggressive bias charging roll (BCR), enhanced photoreceptor life with no compromise in electrical performance characteristics. When a BCR is utilized as the charging device, the photoreceptor surface is generally subject to severe chemical attacks from the corrosive species generated during charging, leading to severe photoreceptor surface wear during cleaning. The photoreceptors that utilize the poly(imide-carbonate)s of the present invention as the charge transport layer binders generally exhibit longer serviceable life such as for example two-fold life enhancement over those that utilize polycarbonate Z binder under similar BCR charging conditions. Various imaging and electrophotographic digital apparatus and processes can incorporate the members of the present invention and wherein the developed images obtained can be of high resolution, especially in, for example high speed, over about 65 prints/copies per minute, machines such as the Xerox Corporation 5090.
The present invention also describes a preparative process for the poly(imide-carbonate)s of the present invention via an interfacial polycondensation reaction using bischloroformates. One of the advantages of this synthetic process over the conventional phosgenation is the elimination of the use of hazardous phosgene or triphosgene that are generally employed in polycarbonate synthesis. The resulting poly(imide-carbonate)s obtained by this process possess an alternating imide and carbonate moieties, and therefore, possess better solubility in common coating solvents such as for example, methylene chloride and tetrahydrofuran, which are generally utilized in the fabrication of charge transport layers. As much as 25 mole percent of the imide functionality can be incorporated into the poly(imide-carbonate) structure without significantly lowering the solubility of the resulting poly(imide-carbonate)s. On the other hand, the poly(imide-carbonate)s prepared via the conventional interfacial phosgenation generally have low solubility. Even a 10 mole percent incorporation of the imide functionality in the poly(imide-carbonate) structure leads to dramatically decreased solubility in the above-mentioned coating solvents.
2. Description of Related Art
Generally, layered photoresponsive imaging members are described in a number of U.S. patents, such as U.S. Pat. No. 4,265,900, the entire disclosure of which is incorporated herein by reference, wherein there is illustrated an imaging member comprised of a photogenerating layer, and an aryl amine hole transport layer. For example, charge transport layers comprised of aryl diamines dispersed in polycarbonates, like MAKROLON.RTM. are known. Examples of photogenerating layer components include trigonal selenium, metal phthalocyanines, vanadyl phthalocyanines, and metal free phthalocyanines. Additionally, there is described in U.S. Pat. No. 3,121,006 a composite xerographic photoconductive member comprised of finely divided particles of a photoconductive inorganic compound dispersed in an electrically insulating organic resin binder. The binder materials disclosed in the '006 patent can comprise resins that are substantially incapable of transporting for any significant distance, injected charge carriers generated by the photoconductive particles.
There are also disclosed in U.S. Pat. No. 3,871,882 photoconductive substances comprised of specific perylene-3,4,9,10-tetracarboxylic acid derivatives. In accordance with the teachings of this patent, the photoconductive layer is preferably formed by vapor depositing the perylene derivatives in a vacuum. Also, there is specifically disclosed in this patent dual layer photoreceptors with perylene-3,4,10-tetracarboxylic acid diimide derivatives, which have spectral response in the wavelength region of from 400 to 600 nanometers. Further, in U.S. Pat. No. 4,555,463, the entire disclosure of which is incorporated herein by reference, there is illustrated a layered imaging member with a chloroindium phthalocyanine photogenerating layer. In U.S. Pat. No. 4,587,189, the entire disclosure of which is incorporated herein by reference, there is illustrated a layered imaging member with a nonhalogenated perylene pigment photogenerating component. Both of the aforementioned patents disclose an aryl amine component as a hole transport layer and wherein there can be selected a resin binder.
Moreover, there are disclosed in U.S. Pat. No. 4,419,427 electrographic recording media with a photosemiconductive double layer comprised of a first layer containing charge carrier perylene diimide pigments, and a second layer with one or more compounds which are charge transporting materials when exposed to light.
U.S. Pat. No. 4,419,427 discloses the use of highly-loaded dispersions of perylene bisimides, with bis(2,6-dichlorophenylimide) being a preferred material, in binder resins as charge generating layers in devices overcoated with a charge transporting layer such as a poly(vinylcarbazole) composition. U.S. Pat. No. 4,429,029 illustrates the use, in devices similar to those of the '427 patent, of bisimides and bisimidazo perylenes in which the perylene nucleus is halogenated, preferably to an extent where 45 to 75 percent of the perylene ring hydrogens have been replaced by halogen. U.S. Pat. No. 4,587,189, the entire disclosure of which is incorporated herein by reference, illustrates layered photoresponsive imaging members prepared with highly-loaded dispersions or, preferably, vacuum evaporated thin coatings of cis- and trans-bis(benzimidazo)perylene (4a, X=1,2-phenylene) and other perylenes overcoated with hole transporting compositions comprised of a variety N,N,N',N'-tetraaryl-4,4'-diaminobiphenyls. U.S. Pat. No. 4,937,164 illustrates the use of perylene bisimides and bisimidazo pigments in which the 1,12-and/or 6,7 position of the perylene nucleus is bridged by one or two sulfur atoms wherein the pigments in the charge generating layers are either vacuum evaporated or dispersed in binder resins and a layer of tetraaryl biphenyl hole transporting molecules.
In U.S. Pat. Nos. 4,869,988 and 4,946,754, the entire disclosures of which are incorporated herein by reference, there are described layered photoconductive imaging members with transport layers incorporating, for example, biarylyl diarylamines, N,N-bis(biarylyl)anilines, and tris(biarylyl)amines as charge transport compounds. In the above-mentioned patents, there are disclosed improved layered photoconductive imaging members comprised of a supporting substrate, a photogenerating layer optionally dispersed in an inactive resinous binder, and in contact therewith a charge transport layer comprised of the above-mentioned charge transport compounds, or mixtures thereof dispersed in resinous binders.
It is also indicated in the aforementioned patents that there may be selected as resin binders for the charge transport molecules those components as illustrated in U.S. Pat. No. 3,121,006 including polycarbonates, polyesters, epoxy resins, polyvinylcarbazole; and also wherein for the preparation of the charge transport layer with a polycarbonate there is selected methylene chloride as a solvent.